1. Field of the Invention
This invention relates to an apparatus for sheet or paper conveyance in an image recording apparatus, and more particularly to a sheet obliquely conveying apparatus for conveying paper obliquely.
2. Related Background Art
The structure for sheet conveyance in an image recording apparatus according to the prior art will hereinafter be described with reference to the accompanying drawings.
FIG. 1 is a perspective view of a paper conveying portion.
In FIG. 1, the reference numeral 1 designates a roller, the reference numeral 2 denotes the rotary center shaft of the roller 1, the reference numerals 3 and 3' designate bearing members supporting the shaft 2, and the reference numeral 4 denotes a cylindrical drive roller which is in contact with the roller 1 and to which rotation is transmitted by a belt or the like.
The width l.sub.1 of the restricting end of the bearing member 3 is somewhat greater than the width l.sub.2 of the restricting end of the bearing member 3' in the tangential direction of the point of contact between the roller 1 and the drive roller 4. The restricting ends 301 and 303 of the bearing members 3 and 3', respectively, are parallel to the rotary center shaft of the drive roller 4 and lie on the same or common straight line.
FIG. 2 is a side view of the sheet conveying portion as a sheet passes therethrough.
The sheet conveying operation will now be described.
As the drive roller 4 is rotated in the direction of solid-line arrow, the roller 1 is also rotated. When the sheet 5 comes into the nip between the roller 1 and the drive roller 4, the sheet is conveyed by the rotation of the drive roller 4. When the sheet 5 is being conveyed, the roller 1 is also rotated and drawn in the tangential direction of the point of contact between it and the sheet 5 due to the friction between the roller 1 and the paper 5.
FIG. 3 is a top plan view of the paper conveying portion when the sheet 5 is conveyed in the direction from A to B. In FIG. 3, the reference numerals 301-304 designate restricting ends. The restricting ends 301 and 303 are parallel to the rotary center shaft of the drive roller 4, and the dot-and-dash line indicates that these restricting ends are on the same straight line.
In FIG. 3, when the sheet 5 is conveyed, the roller 1 is also drawn and the opposite ends of the shaft 2 come into contact with the restricting ends 301 and 302, and therefore, the direction of the rotary shaft of the roller 1 becomes parallel to the direction of the rotary shaft of the drive roller 4, and the paper is conveyed in a direction perpendicular to the rotary shaft of the drive roller 4.
Turning back to FIG. 2, when the drive roller 4 is rotated reversely in the direction of broken-line arrow, the sheet 5 is conveyed reversely and the roller 1 is likewise rotated reversely due to the friction and is drawn in the opposite direction.
FIG. 4 is a top plan view of the sheet conveying portion when the paper is conveyed in the direction from B to D. In FIG. 4, the reference numerals 1-5 and 301-304 designate elements identical those in FIG. 3.
The drive roller is rotated reversely and the sheet 5 is conveyed reversely, whereby the roller 1 is drawn and the shaft 2 comes into contact with the restricting ends 302 and 304 of the bearing members and becomes inclined by an amount corresponding to the gap (about (l.sub.1 -l.sub.2)) and the sheet 5 is conveyed obliquely.
However, in the above-described example of the prior art, the follower roller 1 holds down the sheet 5 by only its gravity and therefore, a slip is liable to occur between the sheet 5 and the roller 1, and this has led to the disadvantage that the sheet cannot be reliably conveyed obliquely.